Heater and gas burner therefor



April 30, 1963 G. D. EDDY HEATER AND GAS BURNER THEREFOR Filed June 5, 1956 2 Sheets-Sheet 1 G. D. EDDY 3,087,484

HEATER AND GAS BURNER THEREFOR 2 Sheets-Sheet 2 PIP 01? ART Juan/0am NA Nrl.

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April 30, 1963 Filed June 5, 1956 United States Patent HEATER AND GAS BURNER THEREFOR George D. Eddy, 2505 N. Pine St, South San Gabriel, Calif.

Filed June 5, 1956, Ser. No. 589,417 9 Claims. Cl. 126-92) This invention relates generally to burners and the heaters in which they are used, and more particularly relates to atmospheric gas burners and their combination in heaters with heat exchangers.

Although the invention particularly relates to, and will be described in connection with, atmospheric gas burners, the novel concept disclosed is readily adaptable for use in connection with burner-s supplied with fluent fuel-s of various consistencies including liquid and solid fuel emulsions, and the utility of the invention is not limited to gaseous fuels of either the natural or manufactured varieties.

In the contemporary atmospheric gas burner art it customary practice to design such burners in various configurations, depending on the use to which they are to be put. Usually, burners comprise a mixer head including the gas and primary air inlets, a mixing tube within which the gas and primary air are mixed to form a combustible mixture, and the burner head provided with burner ports. Port constructions may vary according to design from slotted, ribbon, and drilled port types to those of the jet variety. Additionally, the ports may be vertically or angularly disposed to the vertical, or a combination thereofagain according to engineering design.

However, a feature which is common to all burners known to me is that of their provision for secondary air to be supplied to all sides of the mantle of the burner flame. Thu-s, even though a secondary air passageway may be provided through the central portion of a circular type burner head, for example, there is further provision for secondary air around the periphery of the burner. See pages 134- and 135 of Gaseous Fuels, 1954, second edition, edited by Louis Schnidman and published by the American Gas Association, for illustrations of gas range top burners, contemporary burners, and a sketch of a typical atmospheric gas burner.

I have discovered that for most applications of burners to heaters in which a heat exchanger wall is to be heated by a combustible substance, it is desirable that the heat exchanger wall should form substantially a projection of a wall of the burner port whereby the propagation of both primary and secondary or mantle flame cones from the port is achieved along the boundary layer of the heat exchanger wall. In some of the preferred embodiments of such an arrangement the heat exchanger wall will form susbtantially an extension of the port wall of the burner.

In connect-ion with development work on one embodiment it was also discovered that the coeflicient of heat transfer from the burner flame to the heat exchanger wall was greatly enhanced by admitting the required secondary air to the combustion zone on the side of the flame away from the heat exchanger wall. The aforesaid etiect eflica-cious in connection with a foraminous wall.

Other developments in connection with impervious or solid heat exchanger walls showed that a particularly eflicacious arrangement resulted when a nominal amount of auxiliary or supplementary air (in addition to the secondary air provided as aforesaid) was admitted at the exterior of the flame periphery at its lowermost zone adjacent the burner port.

It is therefore an object of this invention to provide a heater comprising a heat exchanger and a burner in which the admitted secondary air is conducted to the combustion zone with the propagated flame being inter- 3,087,484 Patented Apr. 30, 1963 posed between the heat exchanger wall and the secondary air supply.

Referring to the drawings wherein preferred embodiments are illustrated without intent to limit the scope of the invention thereto:

FIG. 1 is a view in perspective of a radiant heater embodying the present invention;

FIG. 2 is an enlarged cross-section elevation view of the burner and heat exchanger portion of the heater of FIG. 1, taken on the line 22 of FIG. 3;

-FIG. 3 is a top plan view of the burner, taken on the line 33 of FIG. 2;

FIG. 4 is a fragmentary cross-section view of an alternate embodiment of burner and heat exchanger arrangement;

FIG. 5 is a plan view of a fragment of a burner showing enlarged port construction;

FIG. 6 is a cross-section elevation view of a heater comprising an elementary Bunsen type burner, for purposes of comparison with FIG. 7;

FIG. 7 is a cross-section elevation view of a heater comprising an elementary burner of improved type patterned after the present invention, for purposes of comparison with FIG. 6;

!FIG. 8 is a top plan view of a modified form of a heater tor use with a heating air duct, taken on line 8-8 of FIG. 9;

FIG. 9 is a cross-section side elevation view of the heater of FIG. 8, taken on line 9--9 thereof; and

FIG. 10 is a heat transfer diagram showing schematically the temperature differentials. existing across the wall of a heat exchanger and the boundary layer films adjacent thereto.

Referring to FIG. 1, thereis shown a radiant room heater 10 comprising a base portion 12 secured to a pair of upright leg members 14, 16 supported on feet 18, 20. Fixed between the legs 14, 16 and the base 12 is a reflector 22 which may define a surface of revolution, preferably a cylindrical or a spherical segment having a polished surface adapted to reflect radiant heat from the foraminous heat exchanger member 24 of the heater 10 which further comprises the burner member 26.

As better shown in FIG. 2, the heat exchanger 24 comprises a cylindrical standpipe wall 28 of wire mesh having a sheet metal cap 30 provided with a vent opening 31, the cap 30 constituting a closure for the end 32 of the wall 28. The wall 28 may be provided with an eyelet 34 crimped over on each end thereof. The vent 3.1 may be desirable to exhaust the products of combustion, and also may be sized to regulate the percentage of carbon dioxide.

The burner 26 comprises outer and inner cylindrical walls 36, 38, respectively, which define therebetween a port 40 communicating with a plenum chamber 42 defined by the outwardly and downwardly extending portion 44 of the wall 36 and the downwardly and outwardly extending portion 46 of the wall 38, the bottom ends of the walls meeting and being secured together as by brazing or welding to form a leak-proof joint 48. The lower portion 44 of the outer wall 36 is provided with an opening 50 arranged, by means of a pipe coupling 52 brazed or welded to the wall 44, to communicate with the usual mixer head (not shown) for an atmospheric gas burner.

Following conventional practice the mixer head construction is well known and need not be described here. It suffices to say that the atmospheric gas mixture supplied to the plenum chamber 42 is, according to usual practice, dependent upon the gas orifice sizing and the adjustment of the mixer head shutter at the air inlet.

The upper parallel portions 54 and 56 of the outer and inner walls 36, 38, respectively, are equidistantly spaced apart to define the port 40 as aforesaid, the spacing being 3 achieved by means of dimples 60, 62, 64 formed in the upper wall portion 54.

The lower end 66 of the heat exchanger wall 28 abuts the end of the upper portion 54 of the outer burner wall 36. A ring 68 is secured by brazing or welding or by any other preferred means adjacent the lower end 66 of the wall 28, the ring 68 being adapted to be secured to or a snug fit with the outer surface of the upper end 54 of the outer burner wall 36. The inner wall 38 defines a passageway for the admission of secondary air (generally indicated by the arrows 3?) to the zone of combustion (referenced generally at 29).

It is now apparent from the construction shown that (a) the heat exchanger wall 28 constitutes a projection of the outer burner wall 36, and is adjacent thereto, (11) the inner burner wall 38 defines the sole passageway for the admission of secondary air to the combustion chamber, and (c) the port 40 admits the atmospheric gaseous mixture to the combustion chamber for combustion with the flame propagation being achieved between the heat exchanger wall 28 and the inner secondary air zone.

It is an observed fact that the flame of the combustion burns along both the inner and outer surfaces of the foraminous wall 28. The actual nature of the inner flame is not known but it is theorized that the primary inner flame cone may propagate for a substantial distance along and adjacent the wall 28. This is believed to be so because the flame along the outer surface of the wall is bluish in color and adheres very closely to the wall 28, indicating that it comprises the combustion of carbon monoxide formed either by incomplete combustion in the combustion chamber or formed as a dissociation product in the secondary outer flame of mantle. In any event, perfect combustion within the definition set forth by the American Gas Association can be achieved.

The flame along the outer surface of the wall is referenced by the numeral 70 while the primary cone and secondary mantle of the inner flame are referenced by the numerals 72 and 74, respectively, these inner flame configurations being more or less theoretical since they are not observable by reason of being enclosed by the wall 28.

The net effect of the inner and outer flames is a wall 28 that is uniformly hot from bottom to top with the Kelvin temperature adjustable over a wide range by adjusting the gas flow upstream of the mixer head in the usual fashion. Thus, it has been observed that if the flame 70 along the outer surface of the wall is not present, the heating of the wall is not uniform but that irregular areas of relatively cool surface on the lower end of the wall are evident, probably due to the escape of incomplete combustion products through the lower wall.

To overcome this condition there is provided a small passageway through the central bore of the eyelet 34 whereby the flame intercommunicates readily on each side of the wall with one application of the match or other ignition means when the heater is turned on. Preferably, the passageway of the eyelet is relatively small so that the inner flame will not protrude therefrom unduly.

There may be applications of the foregoing burner improvement wherein the atmospheric gas port 40 provides insufficient flow of the combustible mixture to meet design conditions. The designer is further confronted with the problem that the outer and inner walls 54 and 56 may not be designedly spaced sufliciently far apart to permit the required flow without danger of flame flashback through the port.

Under these conditions it is contemplated that conventional burner design practice may be undertaken in accordance with the fragmentary port illustration shown in FIG. 5. In this embodiment the outer port wall 54 and inner port wall 56 are spaced apart the required distance to meet the design statement. In order to reduce the port dimensions of the annular orifice thus indicated without introducing undue flow restrictions, there is secured within the annular orifice and adjacent the ends of the walls 54 and 56 an intermediate annular ribbon 55 of thin sheet metal spaced substantially midway between the walls 54 and 56 by means of the undulating ribbons 53 and 57 of similar thin sheet metal. This practice is well known in the art and requires no further discussion, except to state that the ribbons 53, 55, and 57 separate the annular orifice port into a series of small staggered ports whose depth as governed by the width of the ribbons may be sized for consideration of flame lift, flash-back, ignition velocity, flame height, etc.

The ribbons 53, 55, and 57 may be recessed somewhat below the tops of the burner walls 54 and 56' or may extend beyond the ends, as well as being flush therewith, as preferred for the particular design.

Referring now to FIG. 4, there is shown a construction in which an outer auxiliary or supplementary air source is provided. The auxiliary air thus provided is of the nature of secondary air but it will be observed that it is introduced to the outer side of the flame before the flame propagates to or impinges on the heat exchanger wall. In that respect it resembles a primary air source more than a source of secondary air. The construction according to FIG. 4 is advantageous with heat exchanger walls of the pervious type as described above in connection with FIGS. 1-3, but is particularly adaptable to those of the impervious type.

Here again, the lower end 66 of the heat exchanger wall 28 is brazed or welded to a confining ring 68. And again, there is provided a burner 26 having outer and inner annular walls 36 and 38 defining a port 40 between their upper ends 54 and 56, respectively. Interposed between the burner 26 and the heat exchanger 24 is an annular member 76 comprised of an upper cylindrical portion 78 and an outwardly flaring portion 80 with a lower cylindrical ring member 82 attached to the flaring portion 89 by means of webs 84, which may be three in number and equidistantly disposed around the periphery of the ring 82.

The confining ring 68 is adapted to fit snugly over the outer periphery of the cylindrical portion 78, and may be brazed thereto if desired. Likewise, the ring member 82 is arranged to slide over the outer periphery of the upper end 54 of the outer burner wall 36. Preferably the ports are so fabricated that the inside diameters of the upper end 54 of the wall 36 and of the portion 78 of member 76 are substantially equal whereby the portion 78 and the contiguous heat exchanger wall 29 effectively constitute a projection of the end 54. Also the top edge of the end 54 may extend somewhat above the lower edge of the flaring portion 80 in order to minimize any tendency of the flame to flare outwardly. The inner wall 38 defines the passageway for the secondary air (as shown by the arrows 39) to the combustion zone, as aforesaid in connection with FIG. 2.

It will be observed that the structure provides means for the entrance of auxiliary air to the flame through the passageway defined by the inner wall of the flaring portion 80 and the outer wall 36 of the burner, as indicated by the arrow 83. Further, it is seen that the auxiliary air enters the flame combustion zone prior to the impingement of the flame on the heat exchanger wall 29.

Consideration may now be given to the embodiment of the invention shown in FIGS. 8 and 9. The structure is essentially similar to that of the preceding illustrations, the heat exchanger being comprised of an impervious metal or ceramic material enabling it to be used for heating air by convection primarily rather than radiating. The products of combustion in such a case may be vented directly.

For purposes of illustration the heat exchanger 90 may be comprised of two elongate members 92, 94, each identical and arranged in a duct 96 having sides 98, 100, and top and bottom 102, 104, respectively, for the conduction of air to be heated past the members 92, 94.

The member 92 is comprised of front and rear walls 106, 108, side walls 110, 112, and a top wall 114, all of them straight sided and either fused together or deep drawn of sheet metal to form a continuous wall structure which will be gas tight. The front and rear walls 106, 108 are preferably curved as shown but may be any desired aerodynamic shape which will present low impedance to the movement of the air in the duct 96.

The top wall 114 is provided with an opening 116 communicating with a vent chamber 118 arranged to be connected to a flue (not shown) through which the products of combustion are positively vented.

The lower ends 120 of the heat exchanger walls are flared outwardly and downwardly as shown at 122 and secured by webs 123 to the upper end 124- of the outer wall 126 of the burner 128, in a manner similar to the structure illustrated in FIG. 4.

Aside from being elongate in shape, rather than circular, the burner 128 is similar in all other respects to the burner 76 depicted in FIG. 4, and comprises the outer wall 126 and the inner wall 130 enclosing a plenum chamber 132 for the admission of an atmospheric gas mixture to the port 134 defined by the upper ends 124 and 136 of walls 126 and 130, respectively.

The inner burner wall 130 defines the sole passageway for the admission of secondary air (indicated by the arrows 131) to the heater, and it is again seen that the flame propagated from the port 134 intervenes between the heat exchanger walls 106, 108, 110, 112 and the zone of secondary air, the zone being referenced generally by the numeral 135.

The improvement occasioned by the present invention over the prior art is at once evident when reference is bad to FIGS. 6 and 7. In FIG. 6 there is shown, by way of example, the current teaching of the art wherein secondary air is admitted to the combustion chamber intermediate the flame from the Bunsen type burner and the heat exchanger wall. In FIG. 7 which shows in elementary fashion the teaching of the present invention, there is shown a reversal of the flame and secondary air zone positions, with the addition of the means for admitting auxiliary air as aforesaid.

From FIGS. 6 and 7 it will be perceived that a fundamental difference exists as between the prior art burners and heaters and those of the present invention. That is, FIG. 6 clearly shows the flame and its heat of combustion separated from the heat exchanger wall by the secondary air. Whereas, in FIG. 7 the flame is disposed between the wall and the secondary air zone with a minimum of auxiliary air admitted adjacent the base of the flame and below the exchanger wall. It is believed that the improvement of the present invention over burners and heaters of the prior art arises from these factors: (a) There is less dilution of the combustion products with cool excess air in the zone immediately adjacent the heat exchanger walls, resulting in less tendency for hot spots to develop-hence the average temperature distributed over the heat exchanger wall is higher. (b) Since only that quantity of air required for complete combustion is added at the surface of the flame on the side thereof away from the heat exchanger wall, mixture of air and gas in this Zone takes place more slowly and enhances the tendency to lower the maximum temperature at any one portion of the wall and to raise the temperature over a greater area' The dynamic flame process occurs over a greater area of the heat exchanger wall and closer thereto, hence exerts a greater scrubbing action on the wall with a concurrent tendency to decrease the effective thickness of the boundary layer film 0n the wall. (d) The non-combusted products entrained with the secondary air are generally confined to the central core portion of the heat exchanger, hence are not heated to as great an extent with the result that stack temperatures are lower and less heat is lost up the stack. This necessarily follows since nitrogen is an inert air diluent that constitutes a penalty to efficient combustion. The loss of heat (and consequent lowering of combustion efficiency) by reason of the necessity of heating the nitrogen of the secondary air in known heaters constitutes a considerable penalty that is almost unavoidable where secondary air is admitted to the space between the burner flame and the heat exchanger wall.

With respect to the last factor above-mentioned, reference is made to FIG. 10 which is a schematic of the temperature gradients existing in the usual heat exchanger wall and boundary layer films. The letter T designates the heating or flame temperature, T T1 is the temperature drop across the boundary layer of gas intermediate the flame and heat exchanger wall, Tl-tl is the drop through the heat exchanger wall itself, t1t is the drop occasioned across the outer boundary layer, with t designating the temperature of the useful output of the heat exchanger.

The slope of the temperature gradients T1-t1 and t1t are, in general, not the concern of the present invention. However, factor (a) above-mentioned will raise the starting temperature T and hence all the other temperatures in the gradients. In addition, by causing increased scrubbing of the flame side of the heat exchanger wall by the gases in the flame (as compared with that of entrained secondary air) the boundary layer on the flame side tends to thin out by reason of the turbulence existing therealong whereby the temperature T1 will be increased with the concurrent raising of temperatures t1 and t. Additionally, the slope of the gradient T-Tl tends to flatten with beneficial effects on the following temperatures.

It should be noted that the teaching of the present invention is contrary to accepted practice. That is, it has been stated authoritatively that in the design of gas appliance (and speaking of the burner heat exchanger type for space heaters, for example, and not of industrial type) it is better to avoid impingement of both inner primary cone and outer secondary mantle of the flame on any cold surface. The rationale behind such teaching in the prior art is that incomplete combustion may occur with the formation of carbon monoxide.

However, the present invention has conclusively proven that if such incomplete combustion does occur at any one point it is nullified by a subsequent complete combustion with increased efficiency achieved in the overall heater operation.

I claim:

1. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, one of said wall means closing on itself to define on the side thereof away from. said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the Zone of combustion; and a heat exchanger having a vertically disposed wall with one end contiguous to but displaced from said burner port, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the Zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

2. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, one of said wall means closing on itself to define on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed finely divided foraminous wall with one end contiguous to but displaced from said burner port, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

3. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means each closing upon itself, one within the other and defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, the inner one of said wall means defining on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed wall with one end contiguous to but displaced from said burner port, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by the combustion of said combustible substance and said com- =bustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted "to said heat exchanger wall.

4. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means each closing upon itself, one within the other and defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, the inner one of said wall means defining on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed finely divided foraminous wall with one end contiguous to but displaced from said burner port, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

5. An atmospheric gas burning space heater comprising: an uprightly disposed burner comprised of first and second spaced walls each closing upon itself with one wall interiorly disposed with respect to the other, the space between the walls defining a vertically disposed outlet port having a connection with an atmospheric gas supply, the

upper ends of both said walls terminating substantially adjacent each other at said outlet port, said inner wall defining a generally vertically disposed substantially unrestricted passageway for the admission of secondary air to the combustion zone above said burner; and an uprightly disposed heat exchanger comprised of a vertically disposed heat transfer wall having the lower end thereof disposed generally immediately above the outer wall of said burner, the space between the lower end of said heat transfer wall and the outer wall of said burner defining a further substantially unrestricted passageway for the admission of additional air to the combustion zone, the inner surface of said heat transfer wall lying closely adjacent a projection of said burner port whereby atmospheric gas issuing vertically from said port tends to flow along said inner surface of said heat transfer wall whereupon the flame occasioned by the combustion of the atmospheric gas is propagated substantially entirely adjacent and along said inner surface, the secondary air convected into the interior of the combustion zone tending to expand upon being heated and thereby to confine the flame to that portion of the combustion zone adjacent the said inner surface, whereby substantially all the useful heat of the flame is imparted to said heat transfer wall.

6. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, one of said wall means closing on itself to define on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed wall with one end contiguous to but displaced from said burner port and comprising substantially a projection thereof, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

7. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, one of said wall means closing on itself to define on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed finely divided foraminous wall with one end contiguous to but displaced from said burner port and comprising substantially a projection thereof, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

8. A heater comprising: means for supplying a fluid combustible substance to said heater; a burner having first and second wall means each closing upon itself, one within aosmsa the other and defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second Wall means terminating at said port, the inner one of said wall means defining on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed wall with one end contiguous to but displaced from said burner port and comprising substantially a projection thereof, the displacement of said Wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by the combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

9. A heater comprising: means for supplying a fluid combustible substance to said heater; 3. burner having first and second wall means each closing upon itself, one within the other and defining a vertically disposed port therebetween having a connection with said combustible supply means, one end of said first and second wall means terminating at said port, the inner one of said wall means defining on the side thereof away from said port a substantially unrestricted passageway for the admission of combustion supporting fluid to the zone of combustion; and a heat exchanger having a vertically disposed finely divided foraminous Wall with one end contiguous to but displaced from said burner port and comprising substantially a projection thereof, the displacement of said wall and port defining a further substantially unrestricted passageway for the admission of additional combustion supporting fluid to the zone of combustion, the arrangement of said burner and heat exchanger being such that the combustible substance issuing vertically from said port flows along said heat exchanger wall whereupon the flame occasioned by combustion of said combustible substance and said combustion supporting fluids is propagated substantially entirely adjacent and along said heat exchanger wall, whereby substantially all the useful heat of the flame is imparted to said heat exchanger wall.

References Cited in the file of this patent UNITED STATES PATENTS 558,902 Fennessy Apr. 21, 1896 800,316 McLaughlin Sept. 26, 1905 812,513 Moreno et al Feb. 13, 1906 1,475,450 Schneider Nov. 27, 1923 1,805,066 Andrieux May 12, 1931 1,978,517 Wetherbee Oct. 30, 1934 2,597,062 Cardella et a1 May 20, 1952 2,896,914 Ryan July 18, 1959 FOREIGN PATENTS 246,289 Great Britain July 10, 1925 68,064 Germany Apr. 19, 1893 

1. A HEATER COMPRISING: MEANS FOR SUPPLYING A FLUID COMBUSTIBLE SUBSTANCE TO SAID HEATER; A BURNER HAVING FIRST AND SECOND WALL MEANS DEFINING A VERTICALLY DISPOSED PORT THEREBETWEEN HAVING A CONNECTION WITH SAID COMBUSTIBLE SUPPLY MEANS, ONE END OF SAID FIRST AND SECOND WALL MEANS TERMINATING AT SAID PORT, ONE OF SAID WALL MEANS CLOSING ON ITSELF TO DEFINE ON THE SIDE THEREOF AWAY FROM SAID PORT A SUBSTANTIALLY UNRESTRICTED PASSAGEWAY FOR THE ADMISSION OF COMBUSTION SUPPORTING FLUID TO THE ZONE OF COMBUSTION; AND A HEAT EXCHANGER HAVING A VERTICALLY DISPOSED WALL WITH ONE END CONTIGUOUS TO BUT DISPLACED FROM SAID BURNER PORT, THE DISPLACEMENT OF SAID WALL AND PORT DEFINING A FURTHER SUBSTANTIALLY UNRESTRICTED PASSAGEWAY FOR THE ADMISSION OF ADDITIONAL COMBUSTION SUPPORTING FLUID TO THE ZONE OF COMBUSTION, THE ARRANGEMENT OF SAID BURNER AND HEAT EXCHANGER BEING SUCH THAT THE COMBUSTIBLE SUBSTANCE ISSUING VERTICALLY FROM SAID PORT FLOWS ALONG SAID HEAT EXCHANGER WALL WHEREUPON THE FLAME OCCASIONED BY COMBUSTION OF SAID COMBUSTIBLE SUBSTANCE AND SAID COMBUSTION SUPPORTING FLUIDS IS PROPAGATED SUBSTANTIALLY ENTIRELY ADJACENT AND ALONG SAID HEAT EXCHANGER WALL, WHEREBY SUBSTANTIALLY ALL THE USEFUL HEAT OF THE FLAME IS IMPARTED TO SAID HEAT EXCHANGER WALL. 